This invention relates generally to devices which prevent over-pressurization, and, more particularly to a device which prevents the over-pressurization of vein segments during preparation for grafting.
Autogeneous venous bypass grafts have been accepted as a technique for arterial reconstructive surgery. Originally this graft found use as a conduit to circumvent atherosclerotic occlusive disease in the superficial femoral artery. In more recent times, however, they have also been employed as conduits from the aorta to the distal coronary arteries for coronary artery insufficiency. As more fully explained in Vol. 76, No. 6, pp 1033-1040 of SURGERY dated December 1974, it has become increasingly apparent that venous bypass grafts undergo a substantial loss of patency with time. In fact, veins grafted into the aorta-to-coronary artery position were found to undergo a degenerative process emerging as a subintimal fibrous hyperplasia.
A possible factor involved in the cause of the problem set forth hereinabove are the changes that are induced in the veins used in the graft by methods and apparatus heretofore in use for the preparation of the vein segment prior to the insertion of the vein into the arterial circulation.
Presently, in the preparation of veins for the above-mentioned grafting procedure, distention of the vein is required to localize potential bleeding points so that ligation of these points can be obtained prior to insertion of the graft. During this preparatory procedure a medical syringe is tied directly to the removed vein and a saline solution is injected therein at an arbitrary pressure. Unfortunately, in many instances, this pressure exceeds 500mm/hg and depends upon the rate of injection and skill of the surgeon administrating the saline solution.
It has been shown that such resultant high hydrostatic forces acting upon the vein disrupt the integrity of the intima and media of the vein wall resulting in subsequent failure of the grafted segment from progressive fibrosis and internal hyperplasia.